bygddy, I'm with my87Z. Those "stone stock 416 heads" are the item that makes me go ! With the small chambers, combined with the thin headgasket so you have a good quench, your compression ratio is too high for pump gas. With the small ports and only 1.84" intake valve they don't flow well either unless you have them ported. Unless you have the equipment and skills to port 'em the expense would pay for better heads. Opening the quench by using .041" head gaskets (like the FelPro 1003) would bring your CR down to about 10.4, but that's still marginal for pump gas, especially with the terrible quench.

I was wondering this as well, I had this thought on a wagon I sold last summer and was persuaded not to do it, but I started rethinking it knowing I would only use 94 octane and be somewhat conservitive with timing....using your reccomended head gasket might make this managable tho, and I found a set of L98 alum heads today for 200 bucks complete and clean....so now I'm more confused lol...

Bygddy, I wasn't so much recommending the 1003 head gasket, as stating that it would be a way of opening up the quench to .060 as mentioned by my87Z. All of the compression ratios quoted have been assuming your block has not been decked since you mentioned using .015 thick head gaskets, or at least the ones I gave were. The .015 gaskets are usually used to raise compression on a standard 9.025 deck block with standard compression height (1.56") pistons that are nominally .025 "in the hole". Add the .025 piston deck height to the .015 head gasket thickness and you will have .040 for a good effective quench. This raises questions that I haven't seen addressed here. Has your block been decked? What is the piston deck height measurement? (How far the top of piston is below the block's deck). The piston deck height added to the head gasket thickness is your quench distance, which you want to be .035 - .045. Closer is better, but less then .035 the pistons could hit the heads are higher rpm. The wider it gets the less effective the quench is, decreasing compression ratio but increasing the chance of detonation. Over about .060 there is little, if any, benefit from quench (why I'm not really recommending the thicker head gaskets). If your block has already been "zero decked" (milled to put the piston tops level with the top of the block, or .000 piston deck height) you wouldn't be able to use the .015 head gaskets because your quench would be a too small .015, and it would also make your compression ratio even higher than the 11:1! Depending on whether or not your block has been decked, how much it's been decked if it has, and the compression height of the pistons used ("rebuilder" pistons are usually 1.54 compression height, .020 shorter than the standard 1.56 compression height pistons) your pistons could be anywhere from .000 deck height (level with the block) to .045", or more, "in the hole". With a deck height of .045, even with the thin .015 head gasket, your quench is still a pretty in-effective .060. Back in "the day" before I even knew what quench was I had a 355 built by a big-name machine shop. It never ran like I thought it should. Come to find out later the pistons were .057" in the hole! If I could have put that engine together and ran it with NO HEAD GASKETS I still couldn't have gotten a very effective quench! Add in the fact that I used a cam that was slightly too big for the compression ratio that I THOUGHT I had instead of what I ACTUALLY had, and it was the most disappointing engine I ever owned.

Ideally, for your setup, I would like to see you use some larger chambered heads with a piston/head gasket/block deck height combo that will give a .040 quench and lower the compression ratio to a more pump gas friendly level.

The 416 heads work much much better with full home porting and larger 1.94x 1.60" valves.

Use cooler Champion RV8c plugs (.035" gap) and set timing to 34-36deg BTDC
The distributor could use a recurve.
Make sure the carb is jetted right. If its too lean @WOT it will be more sensitive to knock.
Generally with the lowly performer manifold you want to block off the heat riser passages at the gasket as this manifold tends to run too hot with open heat risers. The plenum gets too hot.

The real cr may not be as high as you think. Many rebuilder flat top pisotns have a reduced compression height at TDC.

The 94 octane gas is pretty good stuff. It may run very well as is.
Why don't you post on how it runs.
If it does prove to knock on 94 once these details have been looked after
its not that hard to fix.
A good opportunity to yank the stock 416 heads and port them yourself. (If I can do it you can too)
Deshrouding -clearance relieving the 416 chamber walls for the larger 1.94x 1.60 valves results in larger 62 64cc chambers.
When you are generous with the porting you gain a good bit of power with these
heads on 350's. That will keep you out of the bars for a few nights.

The stock vacuum advance from a stock GM HEI will be a problem with the agressive high compression ratio.
You would want to get a fully adjustable Crane vac adv unit. Needs custom setup for rate, limit and start point.

I wouldn't have a clue where to start with home porting lol, I have a dremel...! I would love to spend some time porting these, just have no idea where to buy bits, where and how and how much to port...its all voodoo to me....I was going to leave the vacuum advance disconnected on it btw. My driving is typically at 3000rpm all the way to work on the highway, then lots of short light to light bursts....and last question, can you explain blocking off the heat passages in the perfomer? Thanks guys.....really appreciate the help
Dave

Porting has always seemed rather daunting to me too, but if you want to try, a kit like these Standard Abrasives Kits would do it. Combine one of these kits with a die grinder and have at it. (Click on the pictures for the info)

Porting has always seemed rather daunting to me too, but if you want to try, a kit like these Standard Abrasives Kits would do it. Combine one of these kits with a die grinder and have at it. (Click on the pictures for the info)

Any idea if that's something I can buy locally (Canadian) like, a home depot, or a lows sorta deal? And anyone have a basic tutorial on porting these heads?
Thanks

The hell with it, I'm gonna hit the snap on truck at work tommorow and see what bits they have and take a run at it, at this point I have zero money in the heads anyways, should I be sending them to the machine shop before I try this of after? And when blocking off the heat passage on my intake can I simply use thin aluminum Ala: pop can? I figured I would just cut to the proper shape and use that spray gasket sticky stuff to hold it in place until its bolted down?
Dave

The hell with it, I'm gonna hit the snap on truck at work tommorow and see what bits they have and take a run at it, at this point I have zero money in the heads anyways, should I be sending them to the machine shop before I try this of after? And when blocking off the heat passage on my intake can I simply use thin aluminum Ala: pop can? I figured I would just cut to the proper shape and use that spray gasket sticky stuff to hold it in place until its bolted down?
Dave

No pop can material. It will be gone quick.

I believe most intake gasket sets have the block off plates included. I haven't had any luck with them though as they burned right thru.

some intake gasket manufacturers include a cross over plug,use them.Its nice to find a flow bench and test the heads,do 1 port and retest to see if you are on the right direction.Also the guy with the bench can offer words of encouragement as well as direction. have fun,a little help is better than no help.With flow numbers you can better pick a camshaft

some intake gasket manufacturers include a cross over plug,use them.Its nice to find a flow bench and test the heads,do 1 port and retest to see if you are on the right direction.Also the guy with the bench can offer words of encouragement as well as direction. have fun,a little help is better than no help.With flow numbers you can better pick a camshaft

Yah, got all my gaskets today, there is a crossover restricter but it doesn't blokjck it completely....may find a piece of heavier guage tin, or the furnace stuff to plug it....as for porting, I borrowed a compressor, I have an air die grinder I can use, just need some cutting bits, i have little polishing brushes for my dremel and sanding bits as well, just need cutting bits for the die grinder, tryng to do this without spending a dime has been entertaining, heads are getting overnight flushed with clr to clean out the coolant passages, then brake clean, and tide, and a pressure washer, then a light roloc disk to "resurface" lol, then lap the valves, install springs and new seals and viola! Again, my soul intent here is to run down a buddies big dollar roller 355 in his regal using junk I had laying around, in a 750$ vette I pulled out of a feild....he bashes my sht all day...but his expensive junk is so mismatched it should be cake to beat him using the right combo of junk done smart....

While his motor is forged, and all roller, he has 220 runners in alum no name heads, 9.1 comp, a small mild marine cam, a 200r4 with a stock converter, and 370 gears in a ford 9" all in a 84 regal, its missmatched, I have been in it, and light to light, at a legally sanctioned facility of course, I shouldn't need to spray it.....

DO NOT USE Roto discs to "resurface" anything. A sure way to **** up a flat machined surface.
Put those away. Use 80-120-180 on a long sanding block, bodymans file board.
to clean the matting faces if at all.
If they are not flat get them flat milled .005"

I won't I won't lol......sand lightly, .....that's all....oh and Mr Gasket had a complete porting kit for 45$...!!! So that should be in tommorow...need a timing chain, plugs and wires, some thread sealer, and it should be ready to take apart, and reassemble next week!

Got my guages in today, got a small compressor and die grinder, and the porting kit, plus an additional carbide cutting bit with a 6" shank to reach in deeper, will likely dissasemble the heads tommorow and take a run at this! Picked up an L88 hood this week for nothing, so that will get done in satin black and hopefully put on tommorow...grand total invested so far is right around 2000$ and I have everything to assemble the motor next week. This includes the purchase price of the car, various autometer guages, Hurst shifter, TCI shift kit, complete gasket set, headers, dynomax race bullits, Qjet Carb spacer, ....used parts include 416 heads, the quad I'm currently running, or a edelbrock 750 I had left over and a perfomer intake off my Malibu wagon....I'm really hoping I can get this into the 13's with this set up.....but that might be a tad optimistic.....any predictions? Other then the standard " it will blow up" sarcasm?

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.

User Name:

Password

Please enter a password for your user account. Note that passwords are case-sensitive.

Password:

Confirm Password:

Email Address

Please enter a valid email address for yourself.

Email Address:

Log-in

User Name

Remember Me?

Password

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.